A cooling system is disclosed in German Patent Publication DE 44 09 547 A1, to which U.S. Pat. No. 5,482,010 in part corresponds, wherein a thermostatic valve is adjusted to various open positions for varying the coolant temperature of a combined coolant flow to the engine inlet by a control device, and wherein the thermostatic valve control device evaluates operational parameters of the internal combustion engine and ambient parameters of the motor vehicle and adjusts the thermostatic valve as a function of the evaluations. The cooling system further includes a fan that is directly controlled by a fan control device and the thermostatic valve control device communicates a signal to the fan control device which turns the fan on or, alternatively, increases the rpm of the fan if it is already on, when rapid cooling of the coolant passing through the radiator is desired. Furthermore, a timer limits the period of time during which the fan is run (or run at higher rpms) in response to the signal from the thermostatic valve control device.
A cooling system is also disclosed in German Patent Publication DE 195 00 648 A, to which U.S. Pat. No. 5,617,816 corresponds, wherein the thermostatic valve is adjusted to various open positions for varying the coolant temperature of a combined coolant flow to the engine inlet by a control device, and wherein the thermostatic valve control device evaluates operational parameters of the internal combustion engine and ambient parameters of the motor vehicle and adjusts the thermostatic valve as a function of the evaluations. The cooling system further includes a fan that is directly controlled by a fan control device. The fan control device further includes a circuit with a temperature comparison stage in which the actual temperature of the coolant is compared with a set value and which, if the set value is exceeded, forms a temperature signal that is applied to an input of an AND circuit of the fan control device. If a switching signal for adjusting the thermostatic valve to a position for a lower coolant temperature is applied to the other input of the AND circuit, the AND circuit generates a signal that activates the fan.